Anisotropy in turbulent flows

Luca Biferale, Dept. of Physics, University of “Tor Vergata,” Roma

We review the problem of anisotropy and its effects on the statistical properties of turbulent flows at high Reynolds numbers. We discuss the problem of how to disentangle in a systematic way isotropic from anisotropic fluctuations in the analysis of experimental and numerical data. We show that in such a way one can: (i) better assess the problem of universality of isotropic small scale fluctuations; (ii) reveal the presence of intermittency also in the anisotropic components; (iii) understand the slow recovery of isotropy at high Reynolds numbers observed in the experiments. We discuss also some puzzling numerical results about the scaling of longitudinal and transverse velocity fluctuations in isotropic turbulence.

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